Concrete is used extensively in the construction industry and is typically carried to job sites in transit mixer trucks, or on-site mixers, and may be moved at a work site to a point-of-use by concrete pump trucks. When pumping or pouring is complete, a small amount of concrete may remain in the truck, while concrete residues remain on portions of both vehicle mounted and manually operated equipment. Failure to quickly remove the concrete residues allows the concrete to harden thereby complicating the cleanup process and in some cases damaging the equipment. The mixer and pump portions of the truck along with concrete finishing tools must be washed off at the job site after pouring or pumping concrete to allow continued use of the equipment.
At present, concrete residue removal and cleanup is typically accomplished at a temporary disposal location, generally comprising a pit dug in the ground which may in some cases be covered with plastic sheet and surrounded by hay bales. On a concrete pump truck, a plug is removed from the bottom of the concrete pump which allows waste concrete to drain into the disposal pit. The concrete carrier portions are then washed, such as with a hose, to remove concrete residues. A similar operation is performed for transit mixer trucks, and other equipment for handling concrete.
Concrete itself, once hardened, is inert and harmless to the environment. However, the water used to cure concrete, or to clean equipment used to deliver and place concrete, can raise the pH level of surrounding waters and increase the heavy metal content, either of which can in some cases harm living organisms. Therefore, primarily due to environmental concerns and requirements, the concrete is commonly drained into a pit covered with a waterproof sheet, such as a plastic sheet. When the waste concrete materials harden, they are typically removed from the pit and transported to a permanent disposal site. The difficulty with such an approach is that it requires digging a pit, lining the pit, waiting for the waste concrete material to dry, and loading and transporting the dry waste concrete material to another site. In some cases a number of pits need to be dug, during a construction project increasing the impact to the environment. Furthermore, spills can occur while dumping the wet concrete into the pit and washing out the residues, while the sheet material is subject to punctures and tearing, any of which can impact the environment. Consequently, the washing out of concrete equipment must be performed with careful regard for containing runoff from construction sites. As populations have grown and construction has crowded into new areas, building sites are increasingly being considered as possible threats to the environment.
Major concrete installations typically employ transit concrete mixing vehicles, also known as concrete mixers or trucks, to deliver loads of concrete from a concrete production facility to the construction site. The trucks have rotating drums that mix the concrete during transit, so that the concrete is thoroughly mixed and ready for dispensing when the truck reaches the site. After dispensing, a concrete residue remains on the discharge chutes, hoppers, and tools such as shovels and trowels used to handle, guide, and shape the concrete. To prevent the residue from hardening, these components are cleaned on site, typically by rinsing them with water. The resulting residue of this cleaning, i.e. concrete wash product, includes water, dissolved cementatious materials, suspended fine particulates, and larger aggregate. The water is highly alkaline due to the dissolved materials, and consequently is considered a potential groundwater contaminant. Thus, the previous practice of simply dumping concrete wash product onto the ground at the construction site is generally prohibited by local ordinance, state statutes, or regulations.
Mixed concrete and wet cement are frequently utilized in the construction industry either to form various concrete structures or to form both exterior and interior wall surfaces often referred to as stucco finish. These tasks are assisted by various tools and heavy machinery which at the end of its current use needs to be cleaned and prepared for its next use. These periodic washings are dictates by the very nature of concrete and it's very hard structure once set up. Simply, the hardened form of the substance requires that all the working surfaces of the machinery and tools by which it is worked need to be washed before the substance sets up. In the course of a large construction project these repeated washings produce substantial quantities of highly caustic liquid residue that then needs to be safely contained to limit any harm to the environment.
It should be appreciated that the proper disposal of washing fluids is no longer just a matter of good taste or good practice but is currently a subject of profound public concern and regulatory attention. Current damage to our environment is palpable and great public attention is now focused on any processes that either affect the pH of our waters or otherwise contaminate native chemistry balances. Of course, these concerns express themselves in regulatory enactments and enforcement consequences of these regulatory schemes, like the Clean Water Act, have recently resulted in several notoriously large penalty assessments.
Therefore, a need exists for an apparatus for facilitating concrete disposal that allows convenient emptying and cleaning of waste concrete from concrete mixing, hauling, and/or concrete application equipment without subjecting the environment to contamination hazards. The present invention satisfies those needs, as well as others, and overcomes the deficiencies of previously developed concrete disposal solutions.